Different solutions for fuzes and ignitors for munitions, in particular warheads, are previously well known A fuze assembly contains all mechanical, chemical and electrical components to initiate a detonator. According to the state of the art different fuze and igniter arrangements are known for dynamically selecting mode of operation of the warhead or munition. A common practice is to select different modes of operation for different targets.
It is known that a piezoelectric crystal could be used to initiate the ignition of the warhead when the warhead hits a target. In the described known solutions no target identification and/or classification are disclosed.
It is also known that measurement of the deceleration forces of the warhead, when the warhead strikes the target, could be used to initiate the warhead. Such warheads utilize an accelerometer as sensor for measuring the deceleration forces. The information given by the accelerometer is the deceleration force that is proportional to the hardness of the target.
Also known are ignition systems based on relative velocity sensors utilizing at least two switches spaced apart by predetermined distance along the nose of the projectile fuze. The switches are sequentially activated by contact with the target and thus providing electrical signals from which the relative velocity of the projectile could be calculated.
It is also known that sensors or impact fuzes are used for sensing the hardness of a target and, based on the sensed hardness, triggering the ignition of the warhead inside or outside of a target. The impact fuze includes a first sensor for sensing soft targets and a second sensor for sensing hard targets.
Utilizing piezoelectric crystals as an impact sensor in the warhead is previously known. An invention utilizing a piezoelectric sensor as an impact sensor is described in patent document WO 03/051794 A2. The patent document describes a multi-mode haze with at least one sensor that generates an electrical output dependent upon the rate of deceleration when the munition impacts a target. The described multi-mode haze comprises a logic circuit electrical coupled to at least one sensor that discriminates between a soft and a hard target and operates in two operational modes.
A disadvantage with the solution described in WO 03/051794 A2 for target identification is the dependence upon an external power sources for driving the fuze and electronics. The external power source, such as a battery, is expensive and bulky and the performance of the power source is commonly degraded over time.
A further problem with the solution described in WO 03/051794 A2 is the limitation to two operational modes which restricts the use of the warhead.